feat: add -l (list) and -u (unmount) flags

A second sshfsc <alias> call only printed "Already mounted"; tearing
down a mount required ls + fusermount by hand. -l lists active mounts
verified via mountinfo.Mounted, -u <Host> unmounts and removes the
empty mountpoint dir. Flags are mutually exclusive.

main_test.go

@@ -4,6 +4,7 @@
 package main
 
 import (
+	"bytes"
 	"os"
 	"path/filepath"
 	"strings"
@@ -138,3 +139,64 @@ func TestVerifyMountDirRejectsSymlink(t *testing.T) {
 		t.Fatalf("want symlink rejection, got %v", err)
 	}
 }
+
+func TestListMountsMissingBase(t *testing.T) {
+	runtime := t.TempDir()
+	t.Setenv("XDG_RUNTIME_DIR", runtime)
+	var buf bytes.Buffer
+	if err := list_mounts(&buf); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if buf.Len() != 0 {
+		t.Fatalf("want empty output, got %q", buf.String())
+	}
+}
+
+func TestListMountsFiltersUnmounted(t *testing.T) {
+	runtime := t.TempDir()
+	t.Setenv("XDG_RUNTIME_DIR", runtime)
+	base := filepath.Join(runtime, "sshfs")
+	for _, name := range []string{"stale1", "stale2"} {
+		if err := os.MkdirAll(filepath.Join(base, name), 0700); err != nil {
+			t.Fatalf("setup stale dir: %v", err)
+		}
+	}
+	var buf bytes.Buffer
+	if err := list_mounts(&buf); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if buf.Len() != 0 {
+		t.Fatalf("want stale dirs filtered, got %q", buf.String())
+	}
+}
+
+func TestUnmountRejectsBadAlias(t *testing.T) {
+	runtime := t.TempDir()
+	t.Setenv("XDG_RUNTIME_DIR", runtime)
+	err := unmount_sshfs("../etc")
+	if err == nil || !strings.Contains(err.Error(), "disallowed characters") {
+		t.Fatalf("want validation error, got %v", err)
+	}
+}
+
+func TestUnmountNotMountedMissingBase(t *testing.T) {
+	runtime := t.TempDir()
+	t.Setenv("XDG_RUNTIME_DIR", runtime)
+	err := unmount_sshfs("myhost")
+	if err == nil || !strings.Contains(err.Error(), "not mounted") {
+		t.Fatalf("want not-mounted error, got %v", err)
+	}
+}
+
+func TestUnmountNotMountedExistingDir(t *testing.T) {
+	runtime := t.TempDir()
+	t.Setenv("XDG_RUNTIME_DIR", runtime)
+	base := filepath.Join(runtime, "sshfs")
+	if err := os.MkdirAll(filepath.Join(base, "myhost"), 0700); err != nil {
+		t.Fatalf("setup mount dir: %v", err)
+	}
+	err := unmount_sshfs("myhost")
+	if err == nil || !strings.Contains(err.Error(), "not mounted") {
+		t.Fatalf("want not-mounted error, got %v", err)
+	}
+}